A US woman who shot and killed her husband and two adult children before taking her own life is thought to have committed the shocking crime as a result of being ostracised from the religion she was raised in.

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"We make it known that we are able to act everywhere in Turkey," the group said, adding that its militants were ready to act "creatively" across the country.

The group has already claimed three attacks in Turkey this year including a June 7 car bombing in the centre of Istanbul which left 11 people dead. TAK had then warned tourists to stay away from Turkey.

A suicide car bomb attack in March in the capital Ankara left 34 dead.

Police have captured the female suspect, along with two other people in Aksaray province in central Turkey, state-run Anadolu news agency reported on Friday.

The latest capture brings the total number of arrests over the bombing up to six.

Although Turkish officials say TAK is linked to the PKK and used for attacks on civilians, the PKK says it has no control over the group and claims it acts on its own.

The PKK, listed as a terror group by Turkey and its Western allies, has resumed deadly attacks since the collapse of a fragile truce in 2015.

Over 40,000 people have been killed since the PKK first took up arms in 1984.

Thursday's strike was the first bomb attack in Istanbul since the failed July 15 coup seeking to oust the government from power.